The leading hypothesis in addiction research is that exposure to drugs of abuse induces adaptive neu- ronal changes, resulting in addictive behaviors. The many experiments conducted on the basis of this neuro-adaptation theory have identified a huge number of drug-induced cellular changes related to addic- tion. For clinical treatment, however, it is impossible to directly manipulate each of these changes. Our long-term research goal is, thus, to identify the molecular `controllers' that trigger and maintain drug-induced neural adaptations; manipulations of these key molecules may then collectively correct other subordinate pathophysiological cellular changes. This proposal focuses on the N-methyl-D-aspartate receptor (NMDAR), a key molecule that governs multiple forms of neural plasticity and that is a potential molecular controller of addiction-related neural adaptations. Our preliminary studies show that cocaine exposure persistently alters the function of NMDARs in nucleus accumbens (NAc) neurons; experimentally mimicking this change of NMDARs triggers secondary cellular adaptations related to addiction. We hypothesize that this cocaine- induced NMDAR adaptation steers a collection of NMDAR-dependent cellular processes toward addiction- specific adaptations. In this application, we propose an extensive but realistic set of experiments to (1) further characterize cocaine-induced adaptation in NAc NMDARs, (2) examine the underlying molecular mechanisms, and (3) investigate the cellular consequences. To achieve these goals we will use a multi- disciplinary approach utilizing patch-clamp recordings, viral-mediated gene transfer, biochemical assays, and behavioral tests. Relevance to Public Health: By characterizing this novel NMDAR adaptation, our proposed study will define a potential molecular trigger for persistent cocaine-induced adaptations, thus providing relevant mechanistic insights to underpin advances in prevention and treatment of addiction. PUBLIC HEALTH RELEVANCE Project Narrative: The proposed studies will characterize a key molecule that potentially controls a large collection of cocaine-induced, addiction-related neural adaptations. Results from our proposed research will have significant impact on public health because once this `controlling molecule' is defined, therapeutic strategies can be designed accordingly to correct a great number of cocaine-induced cellular adaptations. As such, the findings are expected to lead to novel and effective treatments for human addiction.